The present invention relates to a method and apparatus for producing picture effects by means of a flying spot scanner, for example in a telecine apparatus. In particular, it relates to the provision of angularly displaced or rotating effects. The invention also relates to the production of such effects in a film writer; that is an apparatus which writes images onto film from video signals using a flying spot scanner.
Hitherto, where it has been desired to give the impression of a rotating picture on a television screen or to display an image at an angle to the true orientation of the image on the film scanned by the telecine, this has been achieved by writing a digitised picture information into computer memory pixel-by-pixel. The stored picture information, when complete, is read from the memory under computer control in a different order to that in which it was read in. The controlling computer chooses the sequence of memory addresses and, hence, the order in which the stored pixels are read and displayed. A great many picture effects, including angular and rotary effects can be achieved using such computer based digital techniques. However, these techniques are costly since the volume of memory required is great and complex interpolation is required to generate pixels for positions which are not exactly represented by the stored digital information.
We have appreciated that existing flying spot telecine apparatus may be modified for use as a film writer in which video signals are converted into images on photographic film. Furthermore, we have appreciated that the effects referred to above are also desirable in a film writer and that at present they are subject to the same disadvantages as to cost, complexity and accuracy.
It is an object of the invention to provide a method and apparatus by means of which rotating or angular picture effects may be produced without the need for costly computer memory or complex control programs.
It is a further object of the invention to provide a method and apparatus by which rotating or angular picture effects may be produced in a flying spot film writer.